There have been numerous examples of methods and apparatus for generating synthesis gas from waste materials. There have also been numerous examples of methods and apparatus for generating synthesis gas from waste materials while vitrifying the inorganic portion of the waste materials. These examples include systems described in US and foreign patents that were designed and developed by the inventors and assignee of the present invention as well as others.
Generally, all of these inventions have been designed to recover chemical energy stored in the waste materials in a usable form, typically synthesis gas, either for use as a fuel for powering an engine or as a feedstock for some other chemical operation. Accordingly, it is typical that these systems are operated with some oxidant, such as steam, air, or pure oxygen, to generate synthesis gas from the organic portion of the waste feed stream.
It is also typical that these systems have the dual purpose of providing long term safe storage of any hazardous inorganic portions of the waste materials. Accordingly, many of these systems will be operated in a manner that results in the inorganic portion of the waste feed streams being converted to a vitrified solid that will not leach hazardous constituents into the ground or into aquifers. Among these systems, the most effective in achieving this objective have been systems that allow for the introduction of energy, typically in the form of electrical energy, which is used to process the waste feed streams. As a result, these systems are both producers and consumers of energy. Accordingly, increasing the efficiency in the operation of these systems is an objective that those skilled in the art are always attempting to achieve.
Among these systems, it is also typical that the conversion of the synthesis gas and the solid vitrified material be accompanied by the production of a number of materials that are not desired. These materials include tars, oils, and carbon char that are typically found in the synthesis gas stream. Minimizing the production of undesirable tars, oils, and carbon char is an objective that those skilled in the art are also always attempting to achieve.
Thus, there is a need for improved methods and apparatus for generating synthesis gas from waste materials that achieve any or all of the following objectives: 1) provide greater efficiency in recovering chemical energy stored in the waste materials in a usable form, 2) provide greater efficiency in forming inorganic portions of the waste materials into a form suitable for long term safe storage of any hazardous constituents, and 3) minimize the production of undesirable tars, oils, and carbon char in the synthesis gas.
The present invention achieves all of these objectives.